Atherosclerotic plaque is a relatively common occurrence in these times of rich foods and long life. The plaque produces a stenosis reducing the diameter of the lumen of the artery and restricting blood flow to the region beyond the stenosis. In some instances a balloon catheter may be employed to increase the diameter of the lumen particularly where complete blockage of the artery has not occurred and the plaque has not become calcified or otherwise hardened. In those instances where a balloon catheter cannot be used or cannot be used initially, catheters may be used to bore through the plaque and increase the diameter of the lumen through the stenosis.
The use of steerable catheters to remove atherosclerotic plaque both from coronary as well as peripheral arteries is in increasing use today. In the art today, there are heated catheters, cutting blade catheters and laser catheters all of which may be quite dangerous in use since, if aimed incorrectly or overheated, they can damage the wall of an artery producing serious, if not fatal, injury or cause particles to enter the blood stream.
Various approaches to reducing these hazards have been suggested. Very thin guide wires may be employed to facilitate guiding the catheter to the proper location. With lasers, optical fibers may be employed to conduct the laser energy to the site rather than feed the laser through the arteries whereby to better control various factors such as aim of the beam and the energy supplied by the laser.
Various of these techniques are being employed today but danger of overheating and misdirection are still prevalent although the use of guide wires has materially reduced the danger of mechanical puncture of the wall of an artery. The problem of overheating or of elaborate controls to prevent overheating are still prevalent. Further, there is the danger that solid or liquified plaque may enter the blood stream and produce serious blockage, particularly in small coronary arteries.